Ceramic component having silicon layer and barrier layer

Abstract

A seal system a ceramic component having a surface region defining a first surface roughness, a metallic component situated adjacent the surface region, and a coating system disposed on the surface region. The coating system includes a silicon-containing layer on the surface region and a barrier layer on the silicon-containing layer. The silicon-containing layer has a surface in contact with the barrier layer. The barrier layer has a surface in contact with the metallic component. The surface of the barrier layer has a second surface roughness that is less than the first surface roughness. The barrier layer limits interaction between silicon of the silicon-containing layer and elements of the metallic component. The barrier layer has a coefficient of thermal expansion that is within about 60% of a coefficient of thermal expansion of the ceramic component. A gas turbine engine and a method are also disclosed.

What is claimed is: 
     
       1. A seal system comprising:
 a ceramic component having a surface region defining a first surface roughness; 
 a metallic component situated adjacent the surface region; and 
 a coating system disposed on the surface region, the coating system including a silicon-containing layer and a barrier layer, the silicon-containing layer disposed on the surface region, the barrier layer extending continuously around the ceramic component and the silicon-containing layer, the barrier layer having a first section disposed between the metallic component and silicon-containing layer, a second section disposed on the ceramic component, and an intermediate section that connects the first section and the second section, the first section having a surface in contact with the metallic component, the surface of the first section having a second surface roughness that is less than the first surface roughness, the barrier layer limiting interaction between silicon of the silicon-containing layer and elements of the metallic component, and the barrier layer having a coefficient of thermal expansion that is within 60% of a coefficient of thermal expansion of the ceramic component, 
 wherein the barrier layer includes at least one of hafnon and zircon. 
 
     
     
       2. The seal system of  claim 1 , wherein the coefficient of thermal expansion of the barrier layer is within 40% of the coefficient of thermal expansion of the ceramic component. 
     
     
       3. The seal system of  claim 1 , wherein the metallic component is a nickel- or cobalt-based superalloy. 
     
     
       4. The seal system of  claim 1 , wherein the barrier layer includes at least one of rare earth silicates, alkali silicates alkaline earth silicates, alkaline earth aluminosilicates, mullite, silicon oxynitrides, silicon carbides, silicon oxycarbides, barium-magnesium aluminosilicate, and combinations thereof. 
     
     
       5. The seal system of  claim 4 , wherein the barrier layer includes at least one of strontium aluminosilicate (SAS) and barium-strontium aluminosilicate (BSAS). 
     
     
       6. The seal system of  claim 4 , wherein the second surface roughness is less than 100 Ra. 
     
     
       7. The seal system of  claim 1 , wherein the silicon-containing layer is silicon. 
     
     
       8. The seal system of  claim 1 , wherein the ceramic component has a non-core-gaspath region that faces away from a core gaspath and a core-gaspath region that faces into and bounds the core gaspath. 
     
     
       9. The seal system of  claim 1 , wherein the barrier layer includes hafnon. 
     
     
       10. The seal system of  claim 1 , wherein the barrier layer includes zircon. 
     
     
       11. A gas turbine engine comprising:
 a compressor section; 
 a combustor in fluid communication with the compressor section; and 
 a turbine section in fluid communication with the combustor, and at least one sealing system in the turbine section or the combustor, the at least one sealing system including:
 a ceramic component having a surface region defining a first surface roughness, 
 a metallic component situated adjacent the surface region, and 
 
 a coating system disposed on the surface region, the coating system including a silicon-containing layer and a barrier layer, the silicon-containing layer disposed on the surface region, the barrier layer extending continuously around the ceramic component and the silicon-containing layer, the barrier layer having a first section disposed between the metallic component and silicon-containing layer, a second section disposed on the ceramic component, and an intermediate section that connects the first section and the second section, the first section having a surface in contact with the metallic component, the surface of the first section having a second surface roughness that is less than the first surface roughness, the barrier layer limiting interaction between silicon of the silicon-containing layer and elements of the metallic component, and the barrier layer having a coefficient of thermal expansion that is within 60% of a coefficient of thermal expansion of the ceramic component, 
 wherein the barrier layer includes at least one of hafnon and zircon. 
 
     
     
       12. The gas turbine engine of  claim 11 , wherein the coefficient of thermal expansion of the barrier layer is within 40% of the coefficient of thermal expansion of the ceramic component. 
     
     
       13. The gas turbine engine of  claim 11 , wherein the metallic component is a nickel- or cobalt-based superalloy. 
     
     
       14. The gas turbine engine of  claim 11 , wherein the barrier layer includes at least one of rare earth silicates, alkali silicates alkaline earth silicates, alkaline earth aluminosilicates, mullite, silicon oxynitrides, silicon carbides, silicon oxycarbides, barium-magnesium aluminosilicate, and combinations thereof. 
     
     
       15. The gas turbine engine of  claim 14 , wherein the barrier layer includes strontium aluminosilicate (SAS). 
     
     
       16. The gas turbine engine of  claim 14 , wherein the barrier layer includes barium-strontium aluminosilicate (BSAS). 
     
     
       17. The gas turbine engine of  claim 11 , wherein the silicon-containing layer is silicon. 
     
     
       18. A method of minimizing interaction between components of a seal system, comprising:
 disposing a coating system on a surface region of a ceramic component, the surface region defining a first surface roughness, wherein a metallic component is situated adjacent the surface region, and wherein the coating system includes a silicon-containing layer and a barrier layer the silicon-containing layer disposed on the surface region, the barrier layer extending continuously around the ceramic component and the silicon-containing layer, the barrier layer having a first section disposed between the metallic component and silicon-containing layer, a second section disposed on the ceramic component, and an intermediate section that connects the first section and the second section, the first section having a surface in contact with the metallic component, the surface of the first section having a second surface roughness that is less than the first surface roughness, the barrier layer limiting interaction between silicon of the silicon-containing layer and elements of the metallic component, and the barrier layer having a coefficient of thermal expansion that is within about 60% of a coefficient of thermal expansion of the ceramic component, 
 wherein the barrier layer includes at least one of hafnon and zircon. 
 
     
     
       19. The method of  claim 18 , wherein the barrier layer includes at least one of rare earth silicates, alkali silicates alkaline earth silicates, alkaline earth aluminosilicates, mullite, silicon oxynitrides, silicon carbides, silicon oxycarbides, barium-magnesium aluminosilicate, and combinations thereof.